Ambulatory Blood Pressure May Best Predict Cognitive Decline

Ambulatory blood pressure (BP) may be the best predictor of progressive blood vessel disease that leads to brain damage and cognitive decline, according to a new study.

Researchers at the University of Connecticut School of Medicine (Farmington, USA; medicine.uchc.edu) conducted a prospective study involving 99 subjects (75-89 years of age) to determine the relationships among vascular risk factors, white matter hyperintensity (WMH) volume, and functional status. Ambulatory and clinic BP monitoring, magnetic resonance imaging (MRI), gait studies, and neuropsychological testing were performed at baseline and after 24 months; in all, 72 subjects completed all sets of baseline and follow-up studies. Brain classification into normal white matter and T2-hyperintense WMH volume was performed with semiautomated segmentation, and quantitative measures of mobility and cognitive function were obtained longitudinally.

The results showed that increased ambulatory systolic BP, but not clinic systolic BP, from baseline to two-year follow-up was associated with increased WMH volume over that same period, as well as measures of executive function and processing speed. Similar associations were observed for 24-hour BP, awake BP, and sleep BP, but not for the surge between the sleep and awake time at the 24-month time point. There were no major changes in body weight during the study, and only three patients had severe medical problems, including the development of stroke, heart failure, or valvular disease. The study was published in the November 22, 2011, issue of Circulation.

“For older people who aim to stay as functional as possible during advancing age, their blood pressure averaged out of the office, rather than in the office, might be the most important to target and treat,” said senior author Prof. William White, MD, chief of the division of hypertension and clinical pharmacology. “Interventional studies underway can determine the appropriate level of ambulatory systolic blood pressure for both home and office to prevent the accumulation of cerebrovascular disease in older people.”

Pathological findings in regions of WMH include myelin pallor, tissue rarefaction associated with loss of myelin and axons, and mild gliosis. These lesions are located in the deep white matter, typically sparing subcortical U-fibres, and are often seen together with vessels affected by small vessel disease. The affected vessels are presumed to induce the lesions in deep white matter through chronic hypoperfusion of the white matter and disruption of the blood-brain barrier (BBB), leading to chronic leakage of plasma into the white matter. The prevalence of WMH ranges from 11%-21% in adults aged around 64 and up to 94% at age 82.

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University of Connecticut School of Medicine